Should the Supreme Court strike down the Defense of Marriage Act, which defines marriage as solely between a man and a woman, same-sex couples will see big changes to their finances -- for better and for worse.

Trish McDermott and Julie

While many same-sex couples would save money on their taxes if DOMA is overturned, Trish McDermott and her wife, Julie, would end up owing more if they filed their taxes jointly.

They got married during the brief five-month window in 2008 when gay marriage was legal in California.

They can't file their taxes jointly as a married couple under federal law, but California is a community property state, meaning income must be distributed equally between both partners on state and federal returns. And splitting everything 50/50 actually puts Trish and her wife in even lower tax brackets than if they were to file jointly as a married couple.

But that doesn't stop Trish, who became a stay-at-home mom once her fourth child was born in 2006, from rooting for DOMA's demise. "We are 100% willing to assume the responsibilities of federal marriage rights -- even if it costs more in taxes. We want to be full citizens and assume our full, fair and equal responsibilities," she said.

And it would help them in other ways: eliminating the cost of a tax preparer and, more importantly, alleviating Trish's fear that something could happen to Julie and she would be left to support her children without an income because she wouldn't qualify for Social Security survivor benefits.

"If something happened to Julie, I'm not like all the other families here because I'm completely unentitledto any part of her Social Security -- for reasons that escape me," she said.